EP1154605B1 - Maximum likelihood decoding coherent detecting method - Google Patents

Maximum likelihood decoding coherent detecting method Download PDF

Info

Publication number
EP1154605B1
EP1154605B1 EP01119838A EP01119838A EP1154605B1 EP 1154605 B1 EP1154605 B1 EP 1154605B1 EP 01119838 A EP01119838 A EP 01119838A EP 01119838 A EP01119838 A EP 01119838A EP 1154605 B1 EP1154605 B1 EP 1154605B1
Authority
EP
European Patent Office
Prior art keywords
state
path
metric
phase
states
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP01119838A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP1154605A3 (en
EP1154605A2 (en
Inventor
Fumiyuki c/o NTT DoCoMo inc.Pat & Tradem. Adachi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NTT Docomo Inc
Nippon Telegraph and Telephone Corp
Original Assignee
Nippon Telegraph and Telephone Corp
NTT Mobile Communications Networks Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Telegraph and Telephone Corp, NTT Mobile Communications Networks Inc filed Critical Nippon Telegraph and Telephone Corp
Publication of EP1154605A2 publication Critical patent/EP1154605A2/en
Publication of EP1154605A3 publication Critical patent/EP1154605A3/en
Application granted granted Critical
Publication of EP1154605B1 publication Critical patent/EP1154605B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L25/03178—Arrangements involving sequence estimation techniques
    • H04L25/03184—Details concerning the metric
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0045—Arrangements at the receiver end
    • H04L1/0054—Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H04L27/22—Demodulator circuits; Receiver circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L1/00—Arrangements for detecting or preventing errors in the information received
    • H04L1/004—Arrangements for detecting or preventing errors in the information received by using forward error control
    • H04L1/0045—Arrangements at the receiver end
    • H04L1/0047—Decoding adapted to other signal detection operation
    • H04L1/005—Iterative decoding, including iteration between signal detection and decoding operation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L25/00—Baseband systems
    • H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
    • H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
    • H04L25/03006—Arrangements for removing intersymbol interference
    • H04L2025/0335—Arrangements for removing intersymbol interference characterised by the type of transmission
    • H04L2025/03375—Passband transmission
    • H04L2025/03401—PSK

Definitions

  • the present invention relates to a maximum likelihood coherent detection method which makes the maximum likelihood estimation of a reference signal for coherent detection and the maximum likelihood sequence estimation of a transmitted symbol sequence at the same time through the use of a plurality of received signal samples obtained by sampling a received phase-modulated digital signal at the symbol rate.
  • Coherent detection and differential detection are widely used for the demodulation of phase-modulated signals.
  • the coherent detection provides an excellent error rate performance as compared with the differential detection.
  • To perform the coherent detection it is necessary that the phase of the received carrier be known.
  • the receiving side regenerates the carrier by some means, uses it as a reference signal to coherently detect the modulated phase of the received signal and decides the transmitted data.
  • a multiplying method according to which the received signal is M multiplied to remove therefrom the modulated phase, the multiplied signal is used to effect phase control of a voltage-controlled oscillator (VCO) to generate a signal of a frequency M times higher than the carrier frequency and the frequency of the signal is M demultiplied to regenerate the carrier intended to obtain.
  • VCO voltage-controlled oscillator
  • Another known method is, for example, an inverse modulation method according to which a detected data is used to inversely modulate to remove therefrom the modulated phase and than the carrier is similarly regenerated using the VCO.
  • these methods are disadvantageous in that no fast carrier regeneration is possible because the carrier extracting and regenerating steps form a closed loop using the VCO.
  • the regenerated carrier has a phase uncertainty of 2 ⁇ /M rad.
  • a known signal sequence (several symbols, for instance) is transmitted periodically and used to avoid the uncertainty of the phase.
  • This coherent detection is called absolute coherent detection in the sense of detecting the absolute phase.
  • the bit error rate performance of the absolute coherent detection is superior to that of the differential detection.
  • the difference between the differential detection and the absolute coherent detection in the ratio E b /N o of the received energy per bit necessary for securing a 0.1% bit error rate to the noise power density is as large as 2.5 dB or so.
  • An object of the present invention is to provide an approximate maximum likelihood decoding coherent detection method which makes a sequential transmitted symbol sequence estimation through the use of the Viterbi algorithm but permits reduction of the amount of processing required.
  • Eq. (2) is modified first as follows: where * indicates a complex conjugate and Re[X] the real part of any complex number X.
  • the upper limit of the summation concerning q is n and its maximum value is N-1.
  • the upper limit of the summation concerning q is set to Q( ⁇ N) and the path metric is defined by the following equation:
  • ⁇ n is given by which is the estimate of the carrier (2E s /T) 1 ⁇ 2 exp(j ⁇ ) in Eq. (1), and this value ⁇ n is used as a reference signal for coherent detection of the sample sequence z n .
  • the number of states is M Q in total. M paths extend to each state at time n from M Q states at time n-1 regardless of the value Q.
  • the branch metric that indicates the likelihood of this transition is calculated on the basis of Eq. (5), and the branch metric thus calculated is added to the path metric ⁇ (S n-1 ) in the state S n-1 at time n-1 to obtain the path metric ⁇ (S n ⁇ S n-1 ) of each candidate sequence.
  • Such path metrics are calculated for M states out of the M Q states S n-1 at time n-1 and compared in terms of magnitude to select one path which is most likely to reach one of the states S n at time n.
  • Fig. 3 illustrates an example of a receiver embodying the method of a first embodiment of the invention.
  • a received wave r(t) from an input terminal 11 is fed to a quasi-coherent detector 12, wherein it is quasi-coherently detected by being multiplied by a local signal from a local signal oscillator 13, and the resulting received signal z(t) of the intermediate frequency (or base band) is sampled by a sampling circuit 14 with a fixed period (a symbol period T) to obtain a complex sample Z n of the received signal z(t).
  • the inverse modulating part 15A calculates the reference signal ⁇ n and applies the reference signal to a branch metric calculating part 16.
  • the states at each time n are defined, for example, as M 2 states that are represented by two phases ( ⁇ n , ⁇ n-1 ) at time n and n-1 immediately preceding it.
  • M 4
  • the branch metric calculating part 16 calculates the branch metric that indicates the likelihood of transition from the state S n-1 at the immediately preceding time to the state S n at time n.
  • the Viterbi decoding part 17 sequentially estimates transmitted phase sequences by the Viterbi algorithm.
  • the reference signal adaptive prediction part 15 predicts the reference signal from which variations in the received signal by fading has been removed.
  • the first embodiment is characterized by the estimation of the transmitted phase sequence by the Viterbi algorithm using, as the branch metric, a square error between a reference signal ⁇ n and the received signal sample z n phase-rotated by - ⁇ n and by the adaptive prediction of the reference signal from the received signal sample sequence.
  • the Viterbi decoding part 17 uses the branch metric to calculate, for each state at time n, the path metric that indicates the likelihood of the sequence which reaches the state, then selects the state at the immediately preceding time from which the path most likely to reach each state at time n originates, and stores, for each state, the path history and the path metric in the path memory 17p and the metric memory 17m, respectively. And, the Viterbi decoding part traces back the path of the minimum one of the path metrics in the M 2 states at time n by the fixed number D of point in time and outputs the decoded symbol phased ⁇ n-D .
  • sequence estimation algorithm according to the present invention described above involves such steps as listed below.
  • each state S n at time n is represented by one phase ⁇ n .
  • M survival paths are provided at each point in time.
  • the basic decoding operation by the Viterbi algorithm is the same as in the Fig. 3 embodiment, but the reference signal ⁇ n is calculated by the following equation using the phase at the immediately preceding time on the survival path whose final state is ⁇ n-1 .
  • the receiver configuration in this instance is shown in Fig. 4, in which instead of generating all candidates for the two phases ( ⁇ n-1 , ⁇ n-2 ) representing the M 2 states at time n-1 in the Fig. 3 embodiment, the phase ⁇ n-1 and the subsequent phase at time n-2 on the survival path are read out of the path memory 17p of the Viterbi decoding part 17 and inputted into the inverse modulating part 15A.
  • the inverse modulating part 15A uses the phases ⁇ n-1 and n-2 and the received signal samples z n-q and z n-q to calculate the reference signal ⁇ n by Eq. (9).
  • the other operations are the same as in the Fig. 3 embodiment.
  • the prediction coefficient ⁇ for predicting the reference signal for use at time n can be adaptively determined in such a manner as to minimize the error between the received signal sample and the corresponding linearly predicted value, for example, by tracing back the phase sequence on the survival path which is connected to each state S n-1 at time n-1. As the result of this, each survival path has its own prediction coefficient.
  • the prediction coefficient ⁇ ( ⁇ n-1 ) for predicting the reference signal that is used at time n is selected in such a manner as to minimize a mean square error of an exponential weight that is given by the following equation: where ⁇ is a forgetting factor equal to or smaller than 1.
  • ⁇ ' n-1-i is a reference signal at time n-1-i predicted using the same prediction coefficient ⁇ ( ⁇ n-1 ) at all previous points in time and it is given by the following equation:
  • the abscissa represents the signal energy per bit versus noise power density ratio E b /N o .
  • ideal coherent detection performance CD and the differential detection performance DD for comparison, there are also shown ideal coherent detection performance CD and the differential detection performance DD.
  • the performance 6C by the first embodiment is close to the ideal coherent detection performance within about 1 dB.
  • the difference between the performance 7C by the second embodiment and the ideal coherent detection performance is around 1.5 dB.
  • the amount of processing involved in the second embodiment is approximately 1/4 that in the first embodiment.
  • Fig. 6 there are indicated by the curves 6C and 7C the performance of the first and second embodiments under the Rayleigh fading environment.
  • f D T represents the speed of fading variation
  • f D the maximum Doppler frequency (i.e. moving speed of mobile terminal/wavelength of radio carrier)
  • T one symbol length. Accordingly, 1/T represents the transmission rate. in the differential detection, even if the mean E b /N o is set large, the error rate approaches a fixed value and would not go down below it. In the first and second embodiments, however, the error rate can be reduced by setting the mean E b /N o large.
  • the prediction coefficient ⁇ can be changed in accordance with the fading environment of the received signal, so that the error rate performance is improved as compared with that in the differential detection, regardless of the presence or absence of the fading phenomenon; hence, the performance can be brought close to the ideal coherent detection performance.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Artificial Intelligence (AREA)
  • Power Engineering (AREA)
  • Error Detection And Correction (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)
EP01119838A 1994-06-23 1995-06-23 Maximum likelihood decoding coherent detecting method Expired - Lifetime EP1154605B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP14183494 1994-06-23
JP14183494 1994-06-23
EP95922751A EP0716527B1 (en) 1994-06-23 1995-06-23 Maximum likelihood decoding and synchronous detecting method

Related Parent Applications (1)

Application Number Title Priority Date Filing Date
EP95922751A Division EP0716527B1 (en) 1994-06-23 1995-06-23 Maximum likelihood decoding and synchronous detecting method

Publications (3)

Publication Number Publication Date
EP1154605A2 EP1154605A2 (en) 2001-11-14
EP1154605A3 EP1154605A3 (en) 2003-03-26
EP1154605B1 true EP1154605B1 (en) 2004-09-08

Family

ID=15301227

Family Applications (2)

Application Number Title Priority Date Filing Date
EP01119838A Expired - Lifetime EP1154605B1 (en) 1994-06-23 1995-06-23 Maximum likelihood decoding coherent detecting method
EP95922751A Expired - Lifetime EP0716527B1 (en) 1994-06-23 1995-06-23 Maximum likelihood decoding and synchronous detecting method

Family Applications After (1)

Application Number Title Priority Date Filing Date
EP95922751A Expired - Lifetime EP0716527B1 (en) 1994-06-23 1995-06-23 Maximum likelihood decoding and synchronous detecting method

Country Status (6)

Country Link
US (1) US5619167A (zh)
EP (2) EP1154605B1 (zh)
JP (1) JP3164309B2 (zh)
CN (1) CN1088952C (zh)
DE (2) DE69531928T2 (zh)
WO (1) WO1996000475A1 (zh)

Families Citing this family (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE69532577T2 (de) * 1994-08-08 2004-12-16 Ntt Mobile Communications Network Inc. Verfahren zur verzögerungsdemodulation von dpsk-wellen mit linearer prädiktion
JP3794508B2 (ja) * 1995-01-23 2006-07-05 パイオニア株式会社 デジタルデータ信号再生装置
JPH08287608A (ja) * 1995-04-18 1996-11-01 Fujitsu Ltd 情報再生装置及び最尤等化検出方法
US5841818A (en) * 1996-01-17 1998-11-24 Chung-Chin Chen Decoding method for trellis codes employing a convolutional processor
US5822375A (en) * 1996-05-28 1998-10-13 Wei; Ruey-Yi Method for detecting received signal sequences
FR2753856B1 (fr) * 1996-09-23 1998-12-18 Procede et dispositif de detection de l'erreur sur la frequence d'une porteuse
JPH10322408A (ja) * 1997-03-19 1998-12-04 Sony Corp 受信装置及び信号受信方法
US5940446A (en) * 1997-04-28 1999-08-17 Stanford Telecommunications, Inc. Maximum likelihood detection of MPSK bursts with inserted reference symbols
US6026121A (en) * 1997-07-25 2000-02-15 At&T Corp Adaptive per-survivor processor
FR2767983B1 (fr) * 1997-08-26 1999-10-08 Alsthom Cge Alcatel Procede de decodage et de synchronisation de phase simultanes exploitant le critere de maximum de vraisemblance et dispositif correspondant
AU4459597A (en) * 1997-09-17 1999-04-05 Nokia Telecommunications Oy A doubly differential detector for digital transmission with continuous phase modulation
US5974091A (en) * 1997-10-30 1999-10-26 Communication Network Systems Composite trellis system and method
US6246730B1 (en) 1998-06-29 2001-06-12 Nec Corporation Method and arrangement for differentially detecting an MPSK signal using a plurality of past symbol data
US6535554B1 (en) 1998-11-17 2003-03-18 Harris Corporation PCS signal separation in a one dimensional channel
US6961392B2 (en) * 2000-08-18 2005-11-01 Texas Instruments Incorporated Joint equalization and decoding using a search-based decoding algorithm
US6947748B2 (en) 2000-12-15 2005-09-20 Adaptix, Inc. OFDMA with adaptive subcarrier-cluster configuration and selective loading
US6859488B2 (en) * 2002-09-25 2005-02-22 Terayon Communication Systems, Inc. Detection of impulse noise using unused codes in CDMA systems
CN101946441A (zh) * 2008-02-21 2011-01-12 夏普株式会社 通信装置、通信系统、接收方法和通信方法
CN104639180B (zh) * 2013-11-11 2018-01-02 北京邮电大学 一种译码方法及装置

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0510756B1 (en) * 1991-04-24 1997-12-10 Koninklijke Philips Electronics N.V. Sample tuning recovery for receivers using Viterbi processing
JP2876856B2 (ja) * 1991-10-31 1999-03-31 日本電気株式会社 系列推定方法および装置
JPH05316155A (ja) * 1992-05-08 1993-11-26 Nippon Telegr & Teleph Corp <Ntt> 搬送波再生回路
JP2938289B2 (ja) * 1992-10-30 1999-08-23 エヌ・ティ・ティ移動通信網株式会社 同期検波回路

Also Published As

Publication number Publication date
EP0716527A1 (en) 1996-06-12
EP0716527B1 (en) 2003-10-15
DE69531928T2 (de) 2004-07-22
DE69533494T2 (de) 2005-09-15
EP1154605A3 (en) 2003-03-26
EP0716527A4 (en) 1997-03-26
EP1154605A2 (en) 2001-11-14
WO1996000475A1 (fr) 1996-01-04
CN1129504A (zh) 1996-08-21
DE69533494D1 (de) 2004-10-14
JP3164309B2 (ja) 2001-05-08
DE69531928D1 (de) 2003-11-20
US5619167A (en) 1997-04-08
CN1088952C (zh) 2002-08-07

Similar Documents

Publication Publication Date Title
EP1154605B1 (en) Maximum likelihood decoding coherent detecting method
EP0671837B1 (en) Differential detection method and detector using maximum likelihood estimation
US5029186A (en) Method of demodulation in digital communication systems with multipath propagation
US5774504A (en) Equalization and decoding for digital communication channel
US5481572A (en) Method of and apparatus for reducing the complexitiy of a diversity combining and sequence estimation receiver
EP1042889B1 (en) Computationally efficient sequence estimation
EP0615347A1 (en) Adaptative equalizing receiver and maximum likelihood sequence estimation receiver
EP0457460A2 (en) Spacediversity switching receiver
EP0723353B1 (en) Dpsk wave linear prediction delay detection method
EP1146661A1 (en) Adaptive array communication system and receiver
JP4472904B2 (ja) Ｔｄｍａ無線移動通信のための反復プロセス
JP3689695B2 (ja) Ｃｐｆｓｋ信号の線形近似を利用したｃｐｆｓｋ変調信号用復調器
US6728322B1 (en) Sequential decoder, and receiver using sequential decoder
JP2966673B2 (ja) ダイバーシチ形同期検波回路
US6970520B1 (en) Methods and systems for accumulating metrics generated by a sequence estimation algorithm
JPH05335893A (ja) 等化方法及び装置
JP3141917B2 (ja) Ｄｐｓｋ波適応遅延検波方法
JP2678823B2 (ja) 干渉波除去方法及びそれを使った受信機と通信システム
JP2691949B2 (ja) 最尤判定遅延検波方法及びそれを使った遅延検波器
JPH0851463A (ja) Ｄｐｓｋ波線形予測遅延検波方法
Kamio et al. High bit rate/spl pi//4-QPSK modem with a new equalizer based on sequence estimation for mobile communications
JPH06152674A (ja) 遅延検波装置
JPH06152670A (ja) 同期検波回路
JPH01200852A (ja) 最尤受信機

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20010816

AC Divisional application: reference to earlier application

Ref document number: 716527

Country of ref document: EP

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): DE GB IT SE

RIN1 Information on inventor provided before grant (corrected)

Inventor name: ADACHI, FUMIYUKI C/O NTT DOCOMO INC.PAT,& TRADEM.

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

RIC1 Information provided on ipc code assigned before grant

Ipc: 7H 04L 25/03 B

Ipc: 7H 04L 27/233 A

AK Designated contracting states

Designated state(s): DE GB IT SE

Kind code of ref document: A3

Designated state(s): DE GB IT SE

17Q First examination report despatched

Effective date: 20030528

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

AKX Designation fees paid

Designated state(s): DE GB IT SE

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AC Divisional application: reference to earlier application

Ref document number: 0716527

Country of ref document: EP

Kind code of ref document: P

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE GB IT SE

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

REF Corresponds to:

Ref document number: 69533494

Country of ref document: DE

Date of ref document: 20041014

Kind code of ref document: P

REG Reference to a national code

Ref country code: SE

Ref legal event code: TRGR

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed

Effective date: 20050609

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: SE

Payment date: 20110613

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20110622

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20110621

Year of fee payment: 17

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 20110615

Year of fee payment: 17

REG Reference to a national code

Ref country code: SE

Ref legal event code: EUG

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20120623

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120623

Ref country code: SE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120624

REG Reference to a national code

Ref country code: DE

Ref legal event code: R119

Ref document number: 69533494

Country of ref document: DE

Effective date: 20130101

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20130101

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20120623